Information Thermodynamics for Deterministic Chemical Reaction Networks

TL;DR

This paper extends information thermodynamics to deterministic chemical reaction networks, introducing a mutual information concept for molecular features and deriving second laws for coupled subnetworks, with applications to self-assembly and molecular motors.

Contribution

It develops a framework for applying information thermodynamics to deterministic chemical networks, linking energy and information flows in coupled subnetworks.

Findings

Both systems involve two coupled chemical subnetworks.

External reservoirs drive one subnetwork out of equilibrium.

Information flow acts as an information ratchet only without energy flow.

Abstract

Information thermodynamics relates the rate of change of mutual information between two interacting subsystems to their thermodynamics when the joined system is described by a bipartite stochastic dynamics satisfying local detailed balance. Here, we expand the scope of information thermodynamics to deterministic bipartite chemical reaction networks, namely, composed of two coupled subnetworks sharing species, but not reactions. We do so by introducing a meaningful notion of mutual information between different molecular features, that we express in terms of deterministic concentrations. This allows us to formulate separate second laws for each subnetwork, which account for their energy and information exchanges, in complete analogy with stochastic systems. We then use our framework to investigate the working mechanisms of a model of chemically-driven self-assembly and an experimental light-driven bimolecular motor. We show that both systems are constituted by two coupled subnetworks of chemical reactions. One subnetwork is maintained out of equilibrium by external reservoirs (chemostats or light sources) and powers the other via energy and information flows. In doing so, we clarify that the information flow is precisely the thermodynamic counterpart of an information ratchet mechanism only when no energy flow is involved.